SUMMARY

Performs an inverse discrete Fourier transform.

SYNTAX

IFFT

ALTERNATE FORMS

Purists may use IDFT instead of IFFT.

DESCRIPTION

Data files must have been previously transformed using the FFT command. They may be in either real-imaginary or amplitude-phase format.

HEADER CHANGES

B, DELTA, and NPTS are changed to the beginning frequency, sampling frequency, and number of data points in the transform. The original values of B, DELTA, and NPTS are saved in the header as SB, SDELTA, and NSNPTS and are restored when this command performed.

ERROR MESSAGES

• 1301: No data files read in.
• 1305: Illegal operation on time series file
• 1606: Maximum allowable DFT is

LIMITATIONS

The maximum inverse transform that can currently be performed is 65536 points.

SEE COMMANDS

FFT

LATEST REVISION

October 11, 1984 (Version 9.1)